You're trying to be a team player with an Antagonist; DO NOT TRUST ANYTHING THIS PERSON DOES OR SAYS! STOP! Communicate everything using eMail, Twitter, what ever. Create a communications trail. When someone asks what's going on, simply state, "I think X is having a bad day." Always be freindly, SMILE, ask how that person's day is going. If that person pops off, then pop off with that status on their part of the project. Make communications public. After awhile, and some well documented failures that will occur because the bully can't be both a bully and good at their job. Personal will contact the bully. Your problem is solved.